Free piston motor compressor



Jan.'8, 1952 R. PATERAs PESCARA FREE PISTON MOTOR COMPRESSOR OriginalFiled Nov. 25, 1941 3 Sheets-Sheet 3 IN VE N TUR M zzw. f

ATTORNEY Patented Jan. 8, v1952 z, 5s1,6on

FREE PIsToN Mo'roR COMPRESSOR v Raul Pateras Pescara, Paris, France,assignor to Societe dEtudes vet de Participations, Eau, Gaz,Electricite, Energie, S. A.,'Geneva, Switzerland, a society ofSwitzerland Continuation o! application Serial No. 420,432,

This application August 30, 1946, Serial No. 693.8844.r In FranceSeptem- November 25, 1941.

bei' 3, 1941 12 Claims. l

The present application, which is a continua-f tion of my U. S. patentapplication Ser. No. 420,432, tiled November 25, 1941, now abandoned,the latter being a continuation in part of my U. S. patent applicationSer. No. 182,865, filed December 31, 1937, now abandoned, relates tofreepiston motor-compressors, that is to say machines including at leastone motor part and at least one compressor part, and the recipro-Vcating element or elements of which move with a length of stroke whichis variable within certain limits, at least the main portion of the aircompressed by the compressor part of the motorcompressor serving to feeda receiver, for instance a compressed air reservoir, an air turbine, andso on, distinct from the motor-compressor itself.

Said motor-compressors which deliver compressed air directly from thecompressor cylinder or cylinders thereof to the outside of themotor-compressor must not be confused with freel piston auto-generatorswherein the whole of the air compressed by their compressor part owsthrough the motor cylinder for scavenging this cylinder and mixing withthe combustion gases thereof, this gaseous mixture fed from thePreferred embodiments of the present invention will be hereinafterdescribed, withreierence to the accompanying drawings, given merely byway of example, and in which:

Fig. 1 is a diagrammatical view of a free pistony motor-compressor madeaccording to a first embodiment of the present invention;

Fig. 2 shows a diagram illustrating the working of this machine;

Fig. 3 is a view, similar to Fig. 1, showing a second embodiment of theinvention; and

Fig. 4 is a view, similar to Figs. 1 and 3, shoW- ing a third embodimentof the invention.

In the following description, it will be supposed thatthe invention isapplied to the case of a free piston motor-compressor having a singleaction motor part which works on the two.- stroke principle.

Concerning the general construction of the motor-compressor, it is ofany suitable known type. For instance, according to the embodimentillustrated by Figs.- 1 and 3, it includes a motor cylinder Icooperating with two pistons 21 motor cylinder of the auto-generatorconstituting the final product of the same.

- Anong the motor-compressors thus defined, it is necessary to make adistinction between those in which both the outward and the inwardstrokes are producedby the combustion of fuel in a motor element, thesemachines therefore having a double action motor system, and those inwhich some of these strokes, for instance the outward strokes areproduced by the combustion of fuel in a motor element, while the inwardstrokes are produced by elastic means, in particular by pneumaticcushions capable of storing up, during the outward strokes, a certainamount of energy which is subsequently restored to the free pistons forproducing their inward strokes. In this latter case, the machines have asingle action motor system.

v.Ihe invention is more especially, although not exclusively concerned,among these machines. with those having a single action motor system.

The principal object of the invention is to provide a free pistonmotor-compressor capable of undergoing great load variations,corresponding either to pressure variations of the air delivered `to theoutside of the machine, or to variations of the amount of air suppliedon every piston stroke obtained by varying the length of stroke, or toboth variations at the saine time.

Iii

and 22, reciprocating in opposed directions, and adapted to uncover,when nearing the ends of their outstrokes, inlet ports 3 and exhaustports I.

One of these motor pistons. for instance piston 21. is associated with acompressor piston 5 moving in a cylinder 6, this last mentioned pistonensuring, through its outer face, in the chamber 61 of said cylinder 6,the compression of the air to be produced by the motor-compressor andfed to the outside thereof, while the inner face of piston 5 compresses,in the chamber 62 of the same cylinder, the air to be fed to afluid-tight casing 'I surrounding motor cylinder I.

The other motor piston, to wit 22, is rigid with a piston 8 moving in acylinder 9 and which entraps, in this cylinder, an air cushion whichstores up, during the outward stroke of the motor pistons, a certainamount of energy, which is given back to the pistons during their inwardstrokes, thus permitting said inward strokes to take place.

' 'I'he reciprocating structures '2L-5, on the one hand, and 22-8, onthe other hand, are interconnectedy by synchronizing means, consisting.for instance, of a lever I0 oscillating about a xed axis Il andconnected at its ends, throughconnecting rods I2, with the tworeciprocating structures, respectively.

I provide,I for the feed of fuel to the motor cylinder I, an injectionpump or the like I3, con-- arenoso through a system of levers M, and thequantita tive regulation member i of which is operated, for instance, inresponse to variations or the pressure of compressed airin reservoir iBfed by the chamber 61 of the compressor cylinder 8. Pump I3 is connectedthrough a conduit il with theinjector i8 which opens into motor cylinderi.

In a motor compressor of the kind above de-l scribed. the maximum poweris limited, on the one hand, by the power of the motor part there of,and, on the other hand, by the weight oi air which can be introducedinto the main chamber 61 of the compressor cylinder.

In order to increase the power of a given motor-compressor of this type.it is necessary to supercharge both said chamber and the motor cylinder.

Considering more particularly the supercharging of the motor cylinder,if the air to be fed to said cylinder for scavenging and combustionpurposes were merely compressed by the inner face of compressor piston5, it would be difficult to obtain high value and/or importantvariations of the pressure of said air.

On the other hand, in the case of a two-stroke engine, the utilization,for compressing the Jifeed and scavenging air. of a blower driven by gasturbine feed with the exhaust gases issuing from the motor cylinderwould be generally insuicient for obtaining the necessary air pressures.in view of the fact that the exhaust gases issuing from` such an enginedo not contain a suilicient amount of energy.

In order to avoid these drawbacks, I supercharge chamber 62, in whichthe inner face ci piston 5 compresses the feed and scavenging air to befed to the motor cylinder, by means of a blower I8 which may also serve.to supercharge the main chamber B1 of the compressor part of the machine(see Fig. l). This blower I9 is driven by a gas turbine 2t fed with theexhaust gases passing through the exhaust part 4 of the motor cylinder linto the exhaust com duit.

The discharge pressure oi blower i9 is regulated by the variations ofpower of exhaust gas turbine 20. the power of which decreases when itsinlet area ,increases for the following reasons:

When the input pressure of turbine 2d increases, blower IS delivers airat a higher pressure to compressor unit 5 6. The motor unit l--21-22 istherefore supercharged at a higher pressure and the number ofreciprocations per unit of time of pistons 21-22 slightly increases. sothat the mass of gases iiowing through turbine 2tl per unit of timeslightly increases. But experiments have taught that this increase isvery small and that, for practical purposes, the weight of gases flowingthrough turbine 2t can be considered as constant when the input pressureof turbine 2t varies.

On the other hand, it is known that for a turbine the output of whichopens into the atmosphere, i. e. a medium at constant pressure, which isthe case in the present instance, and through which the rate of flow byweight ci the exhaust gases remains practically constant, which, asabove explained, is also the case, the power delivered by said turbineis the higher as the input pressure is higher. And it is perfectly clearthat when the inlet area of the turbine is reduced, the pressure of theexhaust gases; which are compelled to ow through this area is increased.

position of this abutment 26 is chosen in such v manner that the inletarea of exhaust gas turbine 20 is minimum when piston 23 is appliedagainst said abutment, and this is the `position shown by Fig. l.

The other face of piston 23 is subjected to the action of the pressureexisting in reservoir I8. When this pressure increases above a givenvalue, it produces a displacement oi piston 2lA toward the right and,consequently, an increase of the inlet area or turbine 2U, which, asabove explained, corresponds to a reduction of the power of saidturbine.

Preferably. I provide, on the exhaust pipe leading out .from port d abranch pipe 2l opening into the atmosphere and controlled by a valve 28,which, for certain conditions of operation, permits of discharging acertain portion of the exhaust gases directly into the atmospherewithout passing them through turbine 20.

It follows that, when the power of turbine is maximum, and consequentlywhen the load of the motor-compressor is maximum, the pressure inreservoir i6 is lower than that which exists therein when the machine isrunning on no load or with a low rate of delivery of the compressor.These two pressures determine the limits of regulation of the machine inquestion.

In the diagram of Fig. 2, I have shown, in solid lines and in dottedlines respectively, two different ways of operation of themotor-compressor, the diiierence between these methods of operationbeing due to diierent adjustments of the control device of turbine 20.

In the diagram of Fig. 2. the abscissas are the pressures existing inreservoir i6, while the ordinates represent, on the one hand. the rates45 of delivery lQ into the main chamber 61 of the compressor cylinderand, on the other hand, the

delivery pressures p1 of blower is. The regulation zone thus rangesbetween the reservoir pressure p corresponding to the machine running 6oon maximum load and the reservoir pressure pb corresponding to themachine running on no load. As it results from the diagram of Fig. 2,the rate of delivery Q of the compressor cylinder is maximum when theload is maximum, while it 55 is minimum. or even equal to zero, when theload is zero.

According to the first of the two above mentioned methods of operation,the power of turbine 20, and consequently the compression obtained bymeans of blower i9, gradually de creases from the maximum value thereof(corresponding to a pressure pa in the reservoir i6) to the value whenrunning on no load (corresponding to pressure pb in the reservoir It).

When running on no load (maximum value pb of the pressure in reservoirit), the turbo-blower system Ztl-i9 therefore delivers but little workand the feed pressure to chambers 61 and t2 is Vbut little higher thanthe atmospheric 70 pressure. When the amount of air withdrawn fromreservoir i6 exceeds a given value, the drop of pressure in thisreservoir produces a reduction of the inlet area of turbine 2t, due to adisplacement oi slide valve 22, which corre- ?5 sponds to an increase ofthe pressure in the exhaust pipe of the motor and therefore to anincrease of the'power of the turbo-blower system and of the feedpressure to the chambers 91 and 62 of the compressor.

When the regulation takes place according to the'modiiicat'ionsillustrated. in the diagram of Fig. 2, by the dotted lines, I obtain agradual variation of the feed pressure p1 from the blower within limitscorresponding, on the one hand, to the maximum load of themotor-compressor and, on the other hand, to an intermediate load (forwhich the value of the pressure in reservoir lSis 12), while the feedpressure obtained from the blower remains substantially constant, at 'a'value but little above atmospheric pressure, ior values of the loadranging from this intermediate value to zero.

When the feed pressure obtained from blower I9 is close to theatmospheric pressure, the loss of power in the motor-compressor due tothe working of the turbo-blower unit is practically equal to zero andcan therefore be considered as negligible.

The embodiment of the invention that is illustrated by Fig. 3 of thedrawings diiers, concerning the supercharging of the chambers 61 and 62vof compressor cylinder 6, from the embodiment illustrated by Fig. l,particularly by the fact that the circuit of the air compressed in themain chamber 61 of the compressor is wholly separate from the circuit ofthe feed and scavenging air intended for the motor cylinder and whichpasses through the chamber 62 of the cornpressor cylinder.

In the embodiment oi' Fig. 3, blower I9 feeds air only to the chamber S2of the compressor from which feed and scavenging air is supplied to themotor cylinder. As for the main chamber 6l of the compressor it is fedfrom the outlet of a turbine 29 which is driven by compressed air comingfrom said chamber 61 (after passage through reservoir I6 as shown by thedrawing). the air delivered by the turbine 29 being still under apressure above atmospheric pressure and acting to supercharge thechamber 61. Therefore, this last mentioned air circuit is a closedcircuit. The mean pressure in this circuit is regulated by means of aslide valve 30 which connects conduit 3|, interposed between thedischarge of turbine 29 and chamber 61, either with a source oi airunder pressure such, for instance as a compressed air reservoir 32, orwith the atmosphere, in order thus to decrease or to reduce the weightof air present in this circuit.'

In order simultaneously to regulate the power ofthe turbo-blower unit2I-I8, the right .hand side of.` piston 23 is subjected to the action ofthe pressure existing in said conduit 3| (as shown by the drawing). f

Slide valve 30 may be operated either manually or automatically, forinstance by thev speed governor of turbine 29.

"Of course, the variations of the inlet or discharge pressure of the aircompressed respectively in compressor chambers 81 and 62 necessitate asuitable regulation of the return energy of the reciprocating structuresof the motorcompressor.

This necessity results fromV the fact that this return energy, thegreatest part of which is supplied by pneumatic accumulators 9, servesto produce compression work not only in the motor cylinder but also incompressor chamber 6.

- Inthiembodiment shown by Fig. i, a.; .the

.bers 9.1 and 62 are equalit suiiices to operate .the .control device 34of pneumatic accumulator .9

either by the inlet pressure of said compressor chambers, or by one ofthe discharge pressures of said chambers.

On the contrary. in the embodiment shown by Fig. 3, preferably, Ioperate this control-device of the accumulator in accordance with thevalue of theinlet or discharge pressure both. in main compressor chamber61 and in the other compressor chamber l62.

Furthermore, in both cases, the accumulator control device must becontrolled in accordance with the value of the mean pressure inaccumulator 9 itself.

The return energy ofpneumatic accumulator 9 is varied by increasing ordecreasing the weight of air entrapped in said accumulator. In order toobtain'this increase, the accumulator 9 is connected, through thecontrol device in question, with a source of air under pressure, forinstance with the reservoir I6 which contains the air compressed inchamber B1, while, in order to obtain a reduction of the weight of theair cushion entrapped in accumulator 9, this accumulator is connected,through said control device, for in stance with the atmosphere.

v For this purpose, in the embodiment illustrated by Fig. 1, I providecontrol device 34 with a slide valve 35 adapted to occupy differentpositions such that: Y

v(a) It may keep accumulator 9 closed (posi.- tion of the slide valveshown by Figs. 1 and 3): or

(b) It may connect cushion of air 9, through conduits 35 and 3l withreservoir I6; or again (c) It may connect the same cushion, throughconduits 36 and 38, with the atmosphere.

Slide valve 35 is made rigid with two pistons 39 and 40 movablerespectively in cylinders 4I and 42.

Piston 39 is subjected to the opposed actions of a spring 43 acting onone side thereof and of the mean pressure existing in accumulator 9,acting on the other side of said piston. The mean pressure in questionis transmitted to cylinder 4I through a calibrated conduit `44 extendingbetween said cylinder and conduit 36.

Piston 40 is subjected to the action of the mean pressure existing incasing 1, owing to the provision of a calibrated aperture 45, this meanpressure being substantially equal to the discharge pressure in chamber62.

Finally, I provide, in conduit 31, a check valve 4B intended to preventa ow of air from ac'- cumulator 9 toward reservoir I6, when the pressurein this accumulator is, for certain positions of piston 8, higher thanthe pressure existing in said reservoir IB. I

In this way, I obtain a regulation of thereturn energy supplied byaccumulator 9, whereby this energy is automatically varied in accordancewith the pressure existing in casing vl and of the mean pressure inaccumulator 9.

In order to obtain, in the embodiment shown by Fig. 3, the control ofslide valve 35 in accordance not only with the pressure existing in cas"ing and with the mean pressure in accumulator 9, but also with the inletor discharge pressure in main compression chamber 61, distributing valve35 is controlled, on the one hand, by meansof a piston 391 subjected,through calibrated conduit 44, to the action of the mean pressure existringin'accumulatorsand,on the other hand, by.4

,seneca lthe pressure existing in reservoir i6.

For this purpose, said support te of one of the ends of spring 41 issubjected to the action of a cainv 49 carried by a rod 50 the ends ofwhich are rigid, respectively, with a piston '5i and a, piston 52. Theilrst of these pistons, to wit i, is movable in a cylinder 53 under Atheaction oi the pressure existing in reservoir it, while the secondpistcn, to wit 52, is movable in a cylinder @d under the action, on theone hand, of the mean pressure existing in casing l (which pressure istransl mitted to cylinder E54 through a calibrated ori tice 55) and, onthe other hand, of a spring et."

I will now proceed to describe a third embodh ment ci my invention,shown in Fig. d, in which the compressor part oi the motor-compressor,instead of compressing/f separately the air to be fed to a storagereservoir such as i@ and that to be fed to the motor cylinder of themachine, simultaneously performs both of these compression actions anddelivers a single stream of air a portion of 4which is sent to thereservoir while the remainder is fed to the motor cylinder afterparinvention, it should be well understood that I do not wish to belimited thereto as there might be changes made in the arrangement,disposition and form vof the parts without departing from the principleof the present invention as comprehended within the scope of theappended claims.

What I claim is:

1. A motor-compressor which comprises. in combination, a motor partincluding a motor cyl inder and a motor piston freely movable in saidmotor cylinder, a compressor part including a compressor cylinder and acompressor piston tial expansion, for instance in a receiver such as aturbine.

In this embodiment of the invention, the air from the atmosphere passes4through a blower 60 which discharges it with a certain pressure into theinlet chamber 6i of compressor cylinder 59, which constitutes thecompressor part of the motor-compressor. This compressor cylinder is ofthe double acting type. This air, after compression in said cylinder,issues therefrom through conduit 62.

A portion of this compressed air is sent to reservoir I6 through aconduit tl branching ofi from conduit G2. The remainder is fed throughed to a turbine 63 which is thus operated by said air so as to supplyany desired useful worir. The air in question undergoes in turbine tlbut a partial expansion so that when it leaves turbine 63 throughconduit S4 it is still at a certain pressure. Accordingly this air canbe fed through conduit 64 to the motor cylinder 6l of themotor-compressor, where it acts to scavenge and to supercharge saidmotor cylinder.

The exhaust gases leaving motor cylinder iii pass throughconduiteb,which leads them to turbine 66 which they operate and from which theyescape into the atmosphere. This turbine 66 is mechanically connectedwith blower t@ which feeds compressed air to compressor cylinder 69,whereby said blower d@ is driven by turbine 66.

It should be noted that, in the embodiment i1- lustrated by Fig. 4,there is a single gaseous circuit, including blower 5t, cylinder da,conduit t2, turbine 63, motor cylinder di, conduit @it and turbine 66,from which the gaseous stream is returned to the atmosphere.

In the embodiment of Fig. d, the means for regulating the air cushion inaccumulator cylinder 58 are exactly the same as described with referenceto Fig. 3, the same elements being designated by the same referencecharacters. Cylinder 53 is in communication with reservoir id andcylinder 54 is in communication with the inside of motor cylinder 5lthrough oriilce 55.

In a general manner, while I have, in the above description, disclosedwhat I deem to be practical and emcient embodiments of the presentmovable therein and operatively connected with said motorpiston,pre-compression means operative by said motor piston for feeding airunder pressure to said motor cylinder, means for supercharging saidcompressor part, means for supercharging saidpre-compression meansincluding a blower, a gas-turbine. adapted to be fed by the exhaustgases from said motor cylinder, mechanically connected with said blowerfor driving it, and means for varying the power of said turbine inresponse to variations of the pressure of the air compressed by saidcompressor part, and inversely to saidv variations.

2. A motor-compressor which comprises, in combination, a motor partincluding `a motor, cylinder and a motor piston freely movable in saidmotor cylinder, a compressor part including a compressor cylinder and acompressor piston movable therein and operatively connected with saidmotor piston. pre-compression means operative by said motor piston forfeeding air under pressure to said motor cylinder, means forsupercharging said compressor part, means for supercharging saidpre-compression means including a blower, a gas-turbine, adapted to befed by the exhaust gases from said motor cylinder, mechanicallyconnected with said blower for driving it, and means for varying thepower of said turbine in accordance with one of the 4operating pressuresoi said compressor part.

3. A motor-compressor which comprises, in combination, a motor partincluding a motor cylinder with an exhaust port and a motor pistonfreely movable in said motor cylinder, a compressor part including acompressor cylinder and a compressor piston movable therein andoperatively connected with said motor piston, pre compression meansoperative by said motor piston for feeding air under pressure. to saidmotor cylinder, means for supercharging said pre-compression means andsaid compressor part, the means for supercharging said precompressionmeans including a blower, a gas-turbine, adapted to be fed by theexhaust gases from said motor cylinder, mechanically connected with saidblower for driving it, conduit means connecting the exhaust port of saidmotor cylinder with the intake of said turbine, valve means lforcontrolling the cross section of said conduit means, and meansresponsive to variations of the discharge pressure in said compressorpart for operating said valve means.

4. A motor-compressor which comprises, in combination, a motor partincluding a, motor cylinder with an exhaust port and a motor pistonfreely movable in said motor cylinder, a compresser part including acompressor cylinder and a compressor piston movable therein andoperatively connected with said motor piston, precompression meansoperative by said motor piston for feeding air under pressure to saidmotor cylinder, means for supercharging said pre-compression means, themeans for supercharging said pre-compression means including a blower, agas-turbine, adapted to be feci by the exhaust gases from said motorcylinder, lmechanically connected with said blower for driving it,conduit means connecting the exhaust port o! said motor cylinder withthe intake of said turbine. valve means for. controlling the crosssection of said conduit means, and means responsive to variations of oneof the operating pressures of said compressor part for operating saidvalve means.

5. A motor-compressor which comprises, in combination, a motor partincluding a motor cylinder with an exhaust port, and a motor pistonfreely movable in said motor cylinder, a compressor part including acompressor cylinder and a compressor piston movable therein andoperatively connected with said motor piston, precompression meansoperative by said motor pistori-for feeding air under pressure to saidmotor cylinder, means for supercharging both of said pre-compressionmeans and said compressor part in parallel, said supercharging meansincluding a blower, a gas turbine, adapted to be fed by the exhaustgases from said motor cylinder, mechanically connected with said blowerfor driving it, conduit means connecting the exhaustport of said motorcylinder with the intake of said turbine, valve means for controllingthe cross section of said conduitI means, and means responsive tovariations of the discharge pressure in said compressor part foroperating said valve means so that said cross section is minimum whensaid discharge pressure is minimum and increases when said dischargepressure increases.

6. A motor-compressor which comprises, in combination, a motor partincluding a motor cylinder and motor piston means freely movable in saidmotor cylinder, a compressor part including a. compressor cylinder and acompressor piston movabletherein and operatively connected with saidmotor piston means, pre-compression means operative by said motor pistonfor supplying air under pressure to said motor cylinder, means forsupercharging both of said pre-compression means and said compressorpart, said supercharging means including a blower, and a gas turbine,adapted to be fed by the exhaust gases from said motor cylinder,mechanically connected with said blower for driving it, a pressureaccumulator including a cylinder and a piston movable therein. with amass of air entrapped therebetween, said last mentioned piston beingconnected with said motor piston means in positive mechanical manner, asource of gas under pressure, a slide valve for connecting the inside ofsaid accumulator cylinder either with said source or with theatmosphere, means operative bv the mean pressure in said accumulatorcylinder for urging said slide valve in the direction corresponding tothe connecting of said accumulator with the atmosphere, and meansoperative by the discharge pressure of said pre-compression means. forurging said slide valve in the direction corresponding to the connectingof said accumulator cylinder with said source of gas under'pressure.

7. A motor-compressor which comprises, in combination, a motor partincluding a motor cylinder and motor piston means freely movable in saidmotor cylinder, a compressor part including a compressor cylinder and acompressor piston movable therein and operatively connected with saidmotor piston means, pre-compression means operative by said motor pistonfor supply-l ing air under pressure to said motor cylinder, means forsupercharging said pre-compression means, said supercharging meansincluding a blower, and a gas turbine, adapted to be fed by the exhaustgases from said motor cylinder, me-

chanically connected with said blower for dri ing it, a pressureaccumulator including a cylinder and a. piston movable therein, with amassl of air entrapped therebetween, said last men-l tioned pistonbeingconnected with said motor piston means in positive mechanicalmanner.'

means operative on the one handl by the mean pressure in saidaccumulator cylinder, and on the other hand by the discharge pressure ofsaid pre-compression means for varying the -amount of gas in saidpressure accumulator.

8. A motor-compressor which comprises, in,I

combination, a, motor part including a motor cylinder and motor pistonmeans freely movable in said motor cylinder, a, compressor partincludinga. compressor cylinder and a compressor piston movable therein andVoperatively connected with said motor piston means, an ar,

" motor piston in positive mechanical manner,

means operative on the one hand by the mean pressure in said accumulatorcylinder and on the other hand by the feeding pressure of said motorcylinder for varying the amount of gas in said pressure accumulator.

9. A motor-compressor which comprises, in combination, a motor partincluding a motor cylinder and a, free piston operating in saidcylinder, a compressor part including a compressor cylinder and acompressor piston operating in said compressor cylinder and operativelyconnected to the motor piston, said two pistons forming a unidirectionalunit insofar as the motive stroke is concerned, an arrangement forsuperfeeding the motor part and the compressor part, such arrangementincluding a rotating blower and a gas turbine, means for feeding to saidturbine at least for certain conditions of operation of themotor-compressor the whole of the exhaust gas of the motor cylinder,means mechanically connecting the turbine with thev blower to drive thelatter, a pneumatic energy accumulator acting on said piston unit toassure its return strokes, and means responsive to variations in atleast one of two pressures, to wit that of the gas entering the motorcylinder and that of the gas delivered by the compressor cylinder, tovary the quantity of gas in said accumulator.

l0. A motor-compressor which comprises, in combination, a motor partincluding a motor cylinder and a motor piston freely movable in saidmotor cylinder, a compressor part including a compressor cylinder and acompressor piston movable therein and operatively connected -with saidmotor piston, pre-compression means operative by said motor piston forsupplying air under -pressure to said motor cylinder, means forsupercharging said pre-compression means including a blower. a gasturbine, adapted to be Eli der, mechanically connected with saidblowerior driving it, a receiver machine interposed between' thedischarge oi said compressor part and the intake thereof, whereby airunder pressure .supplied by said compressor part performs a certain it,conduit means connecting the .exhaust vnortv of said motor cylinder withthe intake of amount of work in said receiver machine, where it expands.and returns-to said compressor part to -be again compressed, the partsthrough which said air thus circulates forming a closedvoircuit,

cylinder, a receiver machine interposed between the discharge of saidcompressor part and the intake thereof, whereby air under pressuresupplied by said compressor part performs a certain amount of work insaid receiver machine, where it expands, and returns to said compressorpart t0 be again compressed, the parts through which said air thuscirculates forming a closed circuit, and means for varying the weight ofair in this circuit so as correspondingly to modify the mean pressure insaid closed circuit, means for supercharging said pre-compression meansincluding a blower, a gas turbine, adapted to be fed by the exhaustgases from said motor cylinder, meohanically connected with said .blowerfor driving turbine, valve means for controlling the cross section ofsaid conduit means, andlmeans re sponsive to variations of the pressurein said closed circuit of the compressor part for operating said valvemeans'so that said cross section is minimum when said pressure in theclosed circuit is maximum and inversely.

i2. A motor-compressor according to claim il,

further'including a pneumatic energy accumw,

lator operatively connected with a motor piston for producing the returnstrokes thereof, and means for varying the amount of gas in vsaidaccumulatoraccording both to the pressure in said compressor part andthe pressure in said precompression means.

RAULA PAIERAS PESCARA.

REFERENCES GITED The following references are of record in the le oithis patent:

UNITED STATES PATENT@ Great Britain June 1.6,.1937

